The embodiments described herein relate generally to an electric machine, and more specifically, to an electric machine having encapsulated electronic components.
An electric machine is typically in the form of an electric generator or an electric motor. The machine typically has a centrally located shaft that rotates relative to the machine. Electrical energy applied to coils within the machine initiates this relative motion which transfers the power to the shaft and, alternatively, mechanical energy from the relative motion of the generator excites electrical energy into the coils. For expediency, the machine will be described hereinafter as a motor. It should be appreciated that a machine may operate as a generator and vice versa.
A stationary assembly, also referred to as a stator, includes a stator core and coils or windings positioned around portions of the stator core. It is these coils to which energy is applied to initiate this relative motion which transfers the power to the shaft. These coils are formed by winding wire, typically copper, aluminum or a combination thereof, about a central core to form the winding or coil. An electric current is directed through the coils which induces a magnetic field. It is the magnetic field that initiates this relative motion which transfers the power to the shaft.
Many modern electric machines include a control, for controlling the motor. The control may control the speed and direction of the motor by, for example, controlling the electrical energy going to the coils. The control typically includes a plurality of electrical components.
The electric machine typically includes housing for containing and supporting the stator. While the electrical components may be positioned in a separate control, spaced from the housing of the electric machine, typically, to reduce cost, to reduce space requirements or for other reasons, at least a portion of the electrical components are positioned within the electric machine housing.
Typically, to permit heat generated by the coils and by electrical components to exit the housing, the housing is vented. In many applications a fan may be positioned within the housing to provide for additional air flow to cool the electric machine components. The venting of the housing permits moisture to enter the housing from the environment. In certain applications, such as in air handlers used to cool building, the moisture level within the electric machine or motor housing may be quite high.
Some electrical components and electrical conduits are susceptible to harmful effects caused by high levels of moisture and such moisture may reduce component life. Some electrical machines are exposed to environments with high levels of moisture. Pumping applications, cooling towers and air conditioning chillers are among applications where a high level of moisture is present. To protect component from such moisture, some of the components may be encapsulated in an insulating material, for example a polymer, for example a curable epoxy. The epoxy is applied in a fluid form such that it fills by gravity a large portion of the housing cavity. The epoxy is expensive, making its use in such large quantities to add substantial cost to the motor. It would be desirable to provide encapsulating protection for components in motors while using less epoxy to do so.
The present invention is directed to alleviate at least some of these problems with the prior art.